While direction finding for navigation purposes is becoming less important due to the availability of satellite navigation systems there is a growing demand for determining the location of emitters or signal sources. Before a direction finding method can be applied, it is necessary to detect the existence of a signal emitted by a signal source. The received signals can be extreme weak signals or special signals which have been intentionally generated with characteristics which make the detection of the signals difficult. These kind of special signals are often referred to as low probability of intercept signals.
Accordingly, there is a need for efficient detection of a weak signal or a low probability of intercept signal.